Spatial Moment Analysis for One-Dimensional Nonisothermal Quartz Transport and Dissolution/Precipitation in Fracture-Matrix System

Abstract

This paper presents a spatial-moment analysis of nonisothermal solute transport with simplified dissolution/precipitation of quartz in a single fracture-matrix system using a dual porosity framework. For this purpose, a one-dimensional coupled thermal and solute transport between an injection and a production well is modeled numerically to obtain spatial distribution of temperature and concentration profiles along the fracture. Subsequently, concentration based on first and second spatial moments is evaluated. The effective macrodispersion coefficient is analyzed to study its influence on water velocity, fracture aperture, reservoir diffusion coefficient, reservoir thermal conductivity, reservoir porosity, quartz fraction of the reservoir, and the initial reservoir temperature. The results suggest a non-Fickian behavior that approaches a Fickian behavior due to the effect of coupled matrix diffusion. The mixing characteristics near the injection well are highly sensitive to the above-mentioned parameters at early times, but this mixing effect is subsequently suppressed away from the injection well.